Ascorbic Acid in open Abdominal Aortic Aneurysm repair

INTERVENTION: Participants will be randomised to either 2 g intravenous ascorbic acid or placebo (0.9% saline) infusion for intra‐operative administration. Total duration of treatment is time taken to administer the infusion of the study drug: 20 minutes. All arms are followed up to hospital discharge. CONDITION: Abdominal aortic aneurysm ; Circulatory System ; Aortic aneurysm PRIMARY OUTCOME: Reduction in endothelial dysfunction as measured by plasma von Willebrand Factor (vWF) at fours hours post‐removal of aortic cross clamp. SECONDARY OUTCOME: 1. Systemic endothelial function as assessed by:; 1.1. Adhesion molecules ‐ soluble intercellular adhesion molecule‐1 (sICAM‐1), soluble vascular cell adhesion molecule‐1 (sVCAM‐1), soluble E‐Selectin (sE‐Selectin), measured pre‐operatively and four hours post‐removal aortic crossclamp; 1.2. Urinary albumin:creatinine ratio (ACR), measured pre‐operatively and four hours post‐removal aortic crossclamp; 1.3. Non‐invasive assessment of endothelial function as determined by Pulse Wave Analysis, measured pre‐operatively and four hours post‐removal aortic crossclamp; 2. Pulmonary endothelial dysfunction as measured by pulmonary dead space fraction, measured at post‐intubation and pre‐extubation approximately 1 hour post‐cross clamp removal; 3. Inflammatory response as measured by:; 3.1. Highly sensitive C reactive protein (hsCRP), measured pre‐operatively and four hours post‐removal aortic crossclamp; 3.2. Exhaled breath condensate pH, myeloperoxidase, and leukotriene B4, measured at post‐intubation and pre‐extubation approximately 1 hour post‐cross clamp removal; 4. Oxidative stress as measured by:; 4.1. Serum lipid peroxides, measured pre‐operatively and four hours post‐removal aortic crossclamp; 4.2. Urinary F2 isoprostanes, measured pre‐operatively and four hours post‐removal aortic crossclamp; 4.3. Exhaled breath condensate hydrogen peroxide and 8‐isoprostane, measured pre‐operatively and four hours post‐removal aortic crossclamp INCLUSION CRITERIA: Adult patients (aged 18 years or over, either sex) admitted for elective open repair of abdominal aortic aneurysm in the Royal Victoria Hospital.